Optical communications is a fast advancing technology. As the transmission of information using fiberoptic cables increases, security risks become of growing concern, especially if military or other highly sensitive information is being transmitted. One prior art method of security for optical communications includes manual surveillance. Another prior art method includes installing fiberoptic cables in pressurized pipes, and then generating an alert whenever pressure monitors detect a variation in the pressure beyond some threshold (i.e., whenever a pipe is disturbed). These methods can be inaccurate and generally require added human resources and/or equipment in addition to that needed for installation and operation of the optical network.
Information can be encoded for transmission using amplitude, frequency, and polarization of a lightwave. While the first two have been used for decades, the use of polarization to encode information is relatively recent. Polarization in optical networks has been used for multiplexing, modulation (polarization shift-keying), cryptographic key generation, and as a data encryption tool.
The present invention reduces such external needs and provides a more efficient and effective method of providing enhanced security for fiberoptic communication links and networks by exploiting the inherent physical properties of fiberoptic cables to detect physical “disturbances” in an optical network. More particularly, the present invention relates to using state of polarization information and the birefringence properties of fiber optics to detect and monitor for physical intrusions of fiberoptic based networks.